Fabrication of superhydrophobic/oleophilic starch cryogel via a simple sol-gel immersion process for removing oil from water

Superhydrophobic/oleophilic adsorbents have attracted considerable attention for removing oil spill that poses a serious threat to the aquatic ecosystem. Porous starch–based materials have been proved to have good oil absorption performance, but superhydrophobicity of these materials has not yet been realized. Herein, a superhydrophobic starch-based adsorbent (HTSC) was fabricated through a simple sol–gel immersion process of hexadecyltrimethoxysilane and tetraethyl orthosilicate in the presence of starch cryogel. The adsorbent was simultaneously provided with low surface energy and hierarchical micro/nanostructures via hydrolysis–condensation reaction. HTSC exhibited high water contact angle (>153.0°) and low sliding angle (<8.0°) as well as excellent self-cleaning and anti-fouling properties. The structural support and stable chemical bonding endowed the material with good mechanical and chemical durability. HTSC also possessed reasonable oil adsorption performance (2.6–7.5 g/g), which was dominated by its porosity and followed pseudo-second-order model. Its selective wettability towards oil and water allowed it to be applied for oil removal under water and from the water surface. This novel superhydrophobic starch–based adsorbent shows promising application in oil spill cleanup.